In vitro elution characteristics of gentamicin and vancomycin from synthetic bone graft substitutes.

OBJECTS: Beta tricalciumphosphate pellets loaded with individualized antibiotics may represent novel options in the treatment of osteomyelitis and infectious bone disease. Here, the in vitro antibiotic elution of vancomycin and gentamicin from the synthetic bone graft substitutes Cerasorb(®) and Cerasorb M(®) was tested. METHODS: Antibiotic elution and concentration of gentamcin and vancomycin were measured using photometrically-based measurement and homogeneous particle-enhanced turbidimetric inhibition immunoassays (PETINIA). RESULTS: Initially both materials showed a high release of the loaded antibiotics, with Cerasorb M(®) showing lower release levels for gentamicin and vancomycin than Cerasorb(®). Gentamicin concentrations of Cerasorb M granules and Cerasorb were below the minimum detectiontreshold until day four and six of the experiment respectively. The vancomycin release-level followed a similar pattern, although the vancomycin concentration eluted by Cerasorb M(®) granules stayed above the detection threshold during the experimental time. CONCLUSIONS: Cerasorb(®) and Cersorb M(®) may represent a new treatment option in osteomyelitis and infectious bone disease.

Thermometry during coblation and radiofrequency ablation of vertebral metastases: a cadaver study.

PURPOSE: To evaluate safety of coblation of simulated lytic metastases in human cadaveric vertebral bodies by measuring heat distribution during thermal tissue ablation and comparing it to radiofrequency ablation (RFA). MATERIALS AND METHODS: Three devices were compared: a 10 mm single-needle RFA electrode, a 20 mm array RFA electrode and the coblation device. To simulate bone metastases, a spinal tumor model was used stuffing a created lytic cavity with muscle tissue. Measuring of heat distribution was performed during thermal therapy within the vertebral body, in the epidural space and at the ipsilateral neural foramen. Eight vertebral bodies were used for each device. RESULTS: Temperatures at heat-sensitive neural structures during coblation were significantly lower than using RFA. Maximum temperatures measured at the end of the procedure at the neural foramen: 46.4 °C (± 2.51; RFA 10 mm), 52.2 °C (± 5.62; RFA 20 mm) and 42.5 °C (± 2.88; coblation). Maximum temperatures in the epidural space: 46.8 °C (± 4.7; RFA 10 mm), 49.5 °C (± 6.48; RFA 20 mm) and 42.1 °C (± 2.5; coblation). Maximum temperatures measured within the vertebral body: 50.6 °C (± 10.48; RFA 10 mm), 61.9 °C (± 15.39; RFA 20 mm) and 54.4 °C (± 15.77; coblation). CONCLUSION: In addition to RFA, the application of coblation is a safe method to ablate vertebral lesions with regards to heat distribution at heat-sensitive neural spots. The measured temperatures did not harbor danger of thermal damage to the spinal cord or the spinal nerves.

Scanning electron microscopy investigation of PMMA removal by laser irradiation (Er:YAG) in comparison with an ultrasonic system and curettage in hip joint revision arthroplasty.

The cement often left in the femur socket during hip joint revision arthroplasty is usually removed by curettage. Another method for removing the cement is to use an ultrasonic system, and yet another alternative may be to use a laser system. The aim of these investigations was to determine the pulse rate and pulse energy of the Er:YAG laser for sufficient cement ablation. We also compared the results obtained using the laser with those obtained using an ultrasonic device or curettage by histological and scanning electron microscopy (SEM) investigation of the border zone between the polymethyl methacrylate (PMMA) and unfixed specimens of femoral bone. Therefore we prepared 30 unfixed human femur stems after hip joint replacement and prepared ten sagittal sections from each femur stem (in total 300 sections). Of these 300 specimens, 180 were treated with the Er:YAG laser, 60 with the ultrasonic system and 60 by curettage. The high pulse energy of 500 mJ and a pulse rate of 4 Hz provided the highest PMMA ablation rate, although the boundary surface between PMMA and femoral bone was not as fine-grained as found in samples treated at 15 Hz and 250 mJ. However, the treatment time for the same cement ablation rate with the latter settings was twice that at 4 Hz and 500 mJ. Compared to the boundary surfaces treated with the ultrasonic device or curettage, the laser-treated samples had a more distinct undifferentiated boundary surface between PMMA and femoral bone. After development of the Er:YAG-laser to provide higher pulse energies, it may in the future be an additional efficient method for the removal of PMMA in revision arthroplasty. The Er:YAG laser should be combined with an endoscopic and a rinsing suction system so that PMMA can be removed from the femoral shaft under direct vision.

Hip centralizing forces of the iliotibial tract within various femoral neck angles.

A contentious issue in the literature is the function and the biomechanical properties of the iliotibial tract. On account of this fact the aim was to take a measurement about the hip centralizing forces of the iliotibial tract by using a custom-made hip prosthesis with adjustable femoral neck angles and lengths in an anatomic model. By increasing the collodiaphyseal (CCD) angle (coxa valga) a higher load of the hip joint results. Decreasing the CCD angle (coxa vara) leads to a lower load of the hip joint. In the case of lengthening the femoral neck we saw a considerable increase of the forces along the femoral neck. Furthermore, we registered intraoperatively the subligamentous forces of the iliotibial tract in the height of the greater trochanter to analyse the axial forces into the acetabular cavity. The iliotibial tract showed increasing forces within adduction as well as decreasing forces within abduction of the hip joint. The clinical relevance consists of the predictability of the increasing or decreasing tension band wiring effect of the iliotibial tract in correlation to the CCD angle. The measurement gives the clinical users a benchmark for the expected subligamentous forces of the iliotibial tract and the resulting hip centralizing forces.

Functional cervical MRI within the scope of whiplash injuries: presentation of a new motion device for the cervical spine.

PURPOSE: Frequently following a whiplash injury of the cervical spine, patients suffer from persistent pain symptoms. The MRI will in some of these cases show changes consistent with disk pathology or spinal stenosis, although in most instances the imaging studies will offer no adequate explanation for the described symptoms. The goal of our research was to develop and test a new MRI compatible device that will allow functional imaging of the cervical spine. METHODS: A total of 30 patients with whiplash injuries were evaluated during the first 6 weeks following trauma with the functional MRI. The examination was carried out with a T2-weighted turbo spin-echo sequence utilizing a new apparatus consisting of an inflatable air bag contained in a Plexiglas housing. Thanks to a valve placed outside of the examination room, it was possible to individually regulate the amount of air used to fill the pillow, thereby obtaining a full range of motion between flexion and extension. RESULTS: In 25 cases no pathology was found during this examination. Two patients presented with scarring of the alar ligaments, indicative of a traumatic lesion. In two other instances the images in reclination revealed a bulging disk, while in one case a widening of the disk space was found as a sign for a rupture of the anterior longitudinal ligament. CONCLUSION: Our study was able to demonstrate the applicability of the new functional testing device, which permits a standardized, continuous and dynamic evaluation of the cervical spine in a closed MRI.

Percutaneous cervical disc decompression.

BACKGROUND: Cervical disc nucleoplasty is a significant and clinically demonstrated innovation in percutaneous disc decompression in case of non-herniated disc protrusions or prolpase. It allows a percutaneous decompression via a 19-gauge needle under utilization of the Coblation technique and under C-arm control. Until now the patients suffering of a cervicobrachialgia in cause of a disc prolapse had only the therapeutical solution between conservative treatment and monosegmental spondylodesis or disc prosthesis of the mentioned motion segment. METHODS: We wanted to demonstrate a new and practicable anatomical pathway for reaching the cervical disc prolapse comparable to the technique for discography of the cervical spine. The introducer needle is advanced into the disc under fluoroscopic guidance using a standard anterior-lateral approach. The controller delivers radiofrequency energy to quickly ablate tissue at temperatures between 50 degrees and 60 degrees C. The decompression will be done in ablation mode by rotating the device through 180 degrees for 5 s in the posterior, medial and ventral third of the cervical disc. After failed conservative treatment over an average time period of 3 months we treated 26 patients with a contained herniated prolapse or protrusion with radicular arm pain by percutaneous decompression under utilization of the Coblation technique with a controlled energy plasma-mediated field. A randomized control group of 30 patients was treated alone conservatively with medical and physical therapy in the same period. RESULTS: The average preoperative VAS was 8.8. With a follow-up time of 2-years we found an average pain reduction with the visual pain score (VAS) of 2.3 who had a further check-up. The VAS was checked 24 h, 1 week, 3, 6, 12 and 24 months postoperatively. No complications with this method were seen. Comparable to the surgically treated group the conservative patients have had a VAS of 8.4. Under using conservative treatment with physical therapy, physiotherapy, analgetics and perineural injections we have had a diminution of the VAS to 5.1 after 2 years. CONCLUSION: The percutaneous decompression of the cervical disc protrusion with the Perc DC-Spine Wand by using the Coblation mode is a quick and safe procedure. Furthermore, one may state a persistent pain relief in the follow-up time up to 2 years after the percutaneous decompression of the disc.